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Why is pyridostigmine the most widely used medication in Myasthenia Gravis
What is pyridostigmine? Why is it the most widely used anticholinesterase medication in Myasthenia Gravis?
Pyridostigmine (Mestinon) is slightly longer acting (with a half-life of 4 hours) and has fewer cholinergic side effects than neostigmine bromide and other anticholinesterase preparations.
Unlike physostigmine, pyridostigmine has no unwanted central nervous system effects because it does not cross the blood–brain barrier.
However, some cases of Myasthenia Gravis may be refractory to pyridostigmine but respond to other anticholinesterases.
A long-acting preparation, Mestinon Timespan 180 mg, may alleviate difficulty in swallowing medication in the morning when taken before bedtime but is not as useful for therapy while awake.
A parenteral preparation is also available (2-mg parenteral dose = 60-mg oral dose).
Sources
Walker MB: Myasthenia gravis: A case in which fatigue of the forearm muscles could induce paralysis of the extraocular muscles. Proc Roy Soc Med 31:722, 1938.